From: Eric Dumazet <edumazet@google.com>
To: "David S . Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
Paolo Abeni <pabeni@redhat.com>
Cc: Simon Horman <horms@kernel.org>,
netdev@vger.kernel.org, Ido Schimmel <idosch@nvidia.com>,
Nikolay Aleksandrov <razor@blackwall.org>,
eric.dumazet@gmail.com, Eric Dumazet <edumazet@google.com>
Subject: [PATCH net-next 05/11] bridge: provide lockless access to p->path_cost
Date: Thu, 21 May 2026 13:19:10 +0000 [thread overview]
Message-ID: <20260521131916.3627204-6-edumazet@google.com> (raw)
In-Reply-To: <20260521131916.3627204-1-edumazet@google.com>
Add READ_ONCE()/WRITE_ONCE() annotations around p->path_cost.
This is needed at least for sysfs show_path_cost(), BRCTL_GET_PORT_INFO
and upcoming RTNL avoidance in "ip link" dumps (cf br_port_fill_attrs()).
Signed-off-by: Eric Dumazet <edumazet@google.com>
---
net/bridge/br_if.c | 2 +-
net/bridge/br_ioctl.c | 2 +-
net/bridge/br_netlink.c | 2 +-
net/bridge/br_stp.c | 12 +++++++-----
net/bridge/br_stp_if.c | 2 +-
net/bridge/br_sysfs_if.c | 2 +-
6 files changed, 12 insertions(+), 10 deletions(-)
diff --git a/net/bridge/br_if.c b/net/bridge/br_if.c
index 0bd5cf925fa321b785e3578d6e99d8d7003fa89f..ab012e4762998fe8a133dd551e7f4f0efc6718c6 100644
--- a/net/bridge/br_if.c
+++ b/net/bridge/br_if.c
@@ -77,7 +77,7 @@ void br_port_carrier_check(struct net_bridge_port *p, bool *notified)
if (!test_bit(BR_ADMIN_COST_BIT, &p->flags) &&
netif_running(dev) && netif_oper_up(dev))
- p->path_cost = port_cost(dev);
+ WRITE_ONCE(p->path_cost, port_cost(dev));
*notified = false;
if (!netif_running(br->dev))
diff --git a/net/bridge/br_ioctl.c b/net/bridge/br_ioctl.c
index 766c43b327af830a80fba11c940ba34eb03c50c9..07cfcb821e27ebcb72901a365a3f06491f8b0bc3 100644
--- a/net/bridge/br_ioctl.c
+++ b/net/bridge/br_ioctl.c
@@ -259,7 +259,7 @@ int br_dev_siocdevprivate(struct net_device *dev, struct ifreq *rq,
memcpy(&p.designated_bridge, &pt->designated_bridge, 8);
p.port_id = pt->port_id;
p.designated_port = pt->designated_port;
- p.path_cost = pt->path_cost;
+ p.path_cost = READ_ONCE(pt->path_cost);
p.designated_cost = pt->designated_cost;
p.state = pt->state;
p.top_change_ack = pt->topology_change_ack;
diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c
index 898326c201ef99a1dafda820bfbfe3d428ae2bd3..1b2fbb3a8f9b18ef6479bd3a0c63fe1e761df9a7 100644
--- a/net/bridge/br_netlink.c
+++ b/net/bridge/br_netlink.c
@@ -240,7 +240,7 @@ static int br_port_fill_attrs(struct sk_buff *skb,
if (nla_put_u8(skb, IFLA_BRPORT_STATE, p->state) ||
nla_put_u16(skb, IFLA_BRPORT_PRIORITY, p->priority) ||
- nla_put_u32(skb, IFLA_BRPORT_COST, p->path_cost) ||
+ nla_put_u32(skb, IFLA_BRPORT_COST, READ_ONCE(p->path_cost)) ||
nla_put_u8(skb, IFLA_BRPORT_MODE, mode) ||
nla_put_u8(skb, IFLA_BRPORT_GUARD, !!(p->flags & BR_BPDU_GUARD)) ||
nla_put_u8(skb, IFLA_BRPORT_PROTECT,
diff --git a/net/bridge/br_stp.c b/net/bridge/br_stp.c
index 024210f95468308066827ac2ae71f68f99fa77f5..1367cd3ac4dd6a587d4a6471184453a14af6879c 100644
--- a/net/bridge/br_stp.c
+++ b/net/bridge/br_stp.c
@@ -125,11 +125,12 @@ static int br_should_become_root_port(const struct net_bridge_port *p,
else if (t > 0)
return 0;
- if (p->designated_cost + p->path_cost <
- rp->designated_cost + rp->path_cost)
+ t = p->designated_cost + READ_ONCE(p->path_cost) -
+ (rp->designated_cost + READ_ONCE(rp->path_cost));
+
+ if (t < 0)
return 1;
- else if (p->designated_cost + p->path_cost >
- rp->designated_cost + rp->path_cost)
+ else if (t > 0)
return 0;
t = memcmp(&p->designated_bridge, &rp->designated_bridge, 8);
@@ -187,7 +188,8 @@ static void br_root_selection(struct net_bridge *br)
} else {
p = br_get_port(br, root_port);
br->designated_root = p->designated_root;
- br->root_path_cost = p->designated_cost + p->path_cost;
+ br->root_path_cost = p->designated_cost +
+ READ_ONCE(p->path_cost);
}
}
diff --git a/net/bridge/br_stp_if.c b/net/bridge/br_stp_if.c
index b29dc97b9ad8a5b5c56517d34fe426abd00e2ad6..e5d43492d2dcf0615ee984bc190d7ce2264aaab0 100644
--- a/net/bridge/br_stp_if.c
+++ b/net/bridge/br_stp_if.c
@@ -341,7 +341,7 @@ int br_stp_set_path_cost(struct net_bridge_port *p, unsigned long path_cost)
return -ERANGE;
set_bit(BR_ADMIN_COST_BIT, &p->flags);
- p->path_cost = path_cost;
+ WRITE_ONCE(p->path_cost, path_cost);
br_configuration_update(p->br);
br_port_state_selection(p->br);
return 0;
diff --git a/net/bridge/br_sysfs_if.c b/net/bridge/br_sysfs_if.c
index 1f57c36a7fc097d69cbb8bd7a9348c31be6611aa..0616036a3ce45d45ba817555362f1613f5f9d6cf 100644
--- a/net/bridge/br_sysfs_if.c
+++ b/net/bridge/br_sysfs_if.c
@@ -83,7 +83,7 @@ static int store_flag(struct net_bridge_port *p, unsigned long v,
static ssize_t show_path_cost(struct net_bridge_port *p, char *buf)
{
- return sysfs_emit(buf, "%d\n", p->path_cost);
+ return sysfs_emit(buf, "%d\n", READ_ONCE(p->path_cost));
}
static BRPORT_ATTR(path_cost, 0644,
--
2.54.0.669.g59709faab0-goog
next prev parent reply other threads:[~2026-05-21 13:19 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-21 13:19 [PATCH net-next 00/11] bridge: prepare lockless br_port_fill_attrs() (I) Eric Dumazet
2026-05-21 13:19 ` [PATCH net-next 01/11] bridge: add a READ_ONCE() in br_timer_value() Eric Dumazet
2026-05-21 13:19 ` [PATCH net-next 02/11] bridge: add bridge_flags_bit enum Eric Dumazet
2026-05-21 13:19 ` [PATCH net-next 03/11] bridge: use BR_PROMISC_BIT Eric Dumazet
2026-05-21 13:19 ` [PATCH net-next 04/11] bridge: use BR_ADMIN_COST_BIT Eric Dumazet
2026-05-21 13:19 ` Eric Dumazet [this message]
2026-05-21 13:19 ` [PATCH net-next 06/11] bridge: provide lockless access to p->designated_cost Eric Dumazet
2026-05-21 13:19 ` [PATCH net-next 07/11] bridge: provide lockless access to p->designated_port Eric Dumazet
2026-05-21 13:19 ` [PATCH net-next 08/11] bridge: provide lockless access to p->priority Eric Dumazet
2026-05-21 13:19 ` [PATCH net-next 09/11] bridge: provide lockless access to p->port_id Eric Dumazet
2026-05-21 13:19 ` [PATCH net-next 10/11] bridge: provide lockless access to p->config_pending Eric Dumazet
2026-05-21 13:19 ` [PATCH net-next 11/11] bridge: read p->flags once in br_port_fill_attrs() Eric Dumazet
2026-05-22 8:45 ` [PATCH net-next 00/11] bridge: prepare lockless br_port_fill_attrs() (I) Ido Schimmel
2026-05-22 9:31 ` Eric Dumazet
2026-05-22 9:32 ` Nikolay Aleksandrov
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20260521131916.3627204-6-edumazet@google.com \
--to=edumazet@google.com \
--cc=davem@davemloft.net \
--cc=eric.dumazet@gmail.com \
--cc=horms@kernel.org \
--cc=idosch@nvidia.com \
--cc=kuba@kernel.org \
--cc=netdev@vger.kernel.org \
--cc=pabeni@redhat.com \
--cc=razor@blackwall.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox